Fuel pump

ABSTRACT

A fuel pump includes a plurality of magnets that are disposed circumferentially on an inner surface of a housing of the fuel pump and alternately form different magnetic poles, an armature rotatably disposed inside the permanent magnets, a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature, a pump casing that accommodates and rotatably supports the rotating member, and a discharge port disposed on the pump casing so as to discharge fuel pressurized by the rotation of the rotating member. According to the present invention, an imaginary line extending straight through the discharge port in a flow direction of fuel discharging from the discharge port extends into a circumferential gap between two of said permanent magnets.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon, claims priority from and incorporatesherein by reference the contents of Japanese Patent Applications No.2006-272933 filed on Oct. 4, 2006.

FIELD OF THE INVENTION

The present invention relates to a fuel pump that supplies fuelsuctioned from a fuel tank to an internal combustion engine.

BACKGROUND OF THE INVENTION

Fuel pumps that include a motor section and a pump section that isdriven by the motor section, pumps up and pressurizes fuel for supplyingthe fuel from a fuel tank to an internal combustion engine through theinside of the motor section are well-known, as disclosed inJP-A-5-187382, JP-A-6-167291 and JP-A-6-229390. The motor sectionincludes a plurality of permanent magnets that are positioned about acircumference of its housing so as to form a plurality of magnetic polesin a circumferential direction, an armature disposed inside thepermanent magnets, etc.

As shown in FIG. 4, fuel pressurized in the pump section is dischargedtoward the permanent magnets 310 from a discharge port 302 formed in apump casing 300 of the pump section, which accommodates a rotatingmember. Fuel discharged from the discharge port 302 flows through theinside of the motor section. Specifically, the discharged fuel flowsthrough a gap between an outer surface of the armature and an innersurface of the permanent magnets (not shown), and a gap 312 between theadjacent permanent magnets 310 arranged in the circumferential directionof the inside of the motor section.

However, in the fuel pump, fuel discharged from the discharge port 302of the pump casing 300 cannot flow smoothly into a gap 312 between theadjacent permanent magnets 310 because the fuel collides with an edgesurface 314 of the permanent magnets 310, as shown in FIG. 4. Thisincreases the pressure loss of the fuel flow.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the presentinvention to provide a fuel pump, in which the fuel pressurized in thepump section can flow smoothly into the gap between the adjacentpermanent magnets of the motor section.

According to the present invention, a fuel pump includes a plurality ofmagnets that are disposed circumferentially on an inner surface of ahousing of the fuel pump and alternately form different magnetic poles,an armature rotatably disposed inside the permanent magnets, a rotatingmember disposed on a rotary shaft that is connected with the armatureand rotates with the rotary shaft by rotating the armature, a pumpcasing that accommodates and rotatably supports the rotating member, anda discharge port disposed on the pump casing so as to discharge fuelpressurized by the rotation of the rotating member. According to thepresent invention, an imaginary line extending straight through thedischarge port in a flow direction of fuel discharging from thedischarge port extends into a circumferential gap between two of saidpermanent magnets. In a first embodiment, an imaginary line extending ina flow direction of fuel discharging from the discharge port along aninner inclined surface of the discharge port extends between upstreamends of adjacent permanent magnets. In a second embodiment, an edgebetween the inner inclined surface of the discharge port and an outersurface of the pump casing is below a gap formed between two permanentmagnets.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a longitudinal cross-sectional view showing a fuel pumpaccording to the first embodiment of the present invention;

FIG. 2A is a plan view showing a pump casing of the fuel pump shown inFIG. 1;

FIG. 2B is an enlarged cross-sectional view of a portion around andischarge port of the pump casing of the fuel pump shown in FIG. 1;

FIG. 3A is a plan view showing a pump casing of the fuel pump accordingto the second embodiment of the present invention;

FIG. 3B is an enlarged cross-sectional view of a portion around andischarge port of the pump casing of the fuel pump according to thesecond embodiment of the present invention;

FIG. 4A is a plan view showing a pump casing of a conventional fuelpump; and

FIG. 4B is an enlarged cross-sectional view of a portion around andischarge port of the pump casing of the conventional fuel pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A fuel pump 10 according to the first embodiment will be described withreference to FIGS. 1 and 2.

The fuel pump 10 is an in-tank type turbine pump that is usuallyaccommodated in a fuel tank (not shown) of a vehicle, such as two-wheelvehicle or four-wheel vehicle. The fuel pump 10 pressurizes fuelsuctioned from the fuel tank, and supplies the pressurized fuel to aninternal combustion engine.

The fuel pump 10 includes a pump section 12 and a motor section 13 thatdrives the pump section 12. The pump section 12 and the motor section 13are housed in a housing 14. A casing cover 20 is caulked at the outerperiphery thereof by the edge portion of the housing 14. With thisstructure, the pump casing 22 can be held between the casing cover 20and a step 15 formed on the inner surface of the housing 14.

The pump section 12 is a turbine pump that includes the casing cover 20,a pump casing 22 and an impeller 30. The pump section 12 is arranged onthe upstream side of the motor section 13 in the axial direction of therotation axis of an armature 50 of the motor section 13. The impeller 30(as a rotating member) is assembled on a rotary shaft 56 (as a rotationaxis). The casing cover 20 and the pump casing 22 form a casing member,which accommodates and rotatably supports the impeller 30. The casingcover 20 has a fuel suction port 200, through which fuel is pumped upfrom the fuel tank into pump passages 202 a,202 b. The fuel passages 202a,202 b are formed as C-shaped grooves along an outer edge of theimpeller 30 in the casing cover 20 and the pump casing 22, respectively.The impeller 30 is disc-shaped, and a plurality of blades and bladeditches are alternately formed at the outer edge of the impeller 30.When the impeller 30 rotates with the rotary shaft 56 by rotating thearmature 50 of the motor section 13, fuel flows out of the blade ditchesof the impeller 30 toward the inner surface of the fuel passage 202a,202 b. The fuel returns to the blade ditches from the inner surface ofthe fuel passage 202 a,202 b and flows out of the blade ditches of theimpeller 30 again. After the fuel repeats the above flowing out andreturning, the fuel is pressurized and forms a circulating flow in thefuel passage 202 a,202 b. Thus, fuel can be pumped up through the fuelsuction port 200 and be pressurized in the fuel passage 202 a,202 b bythe rotating impeller 30. Fuel pressurized in the fuel passage 202 a,202b flows together in a discharge port 204 of the pump casing 22, and isdischarged into the motor section 13 through the discharge port 204.

The motor section 13 includes permanent magnets 40 a,40 b, the armature50, a commutator 60, a brush 80 and a choke coil 82. Permanent magnets40 a,40 b have arc-shaped cross sections, respectively, and are fixed onthe inner surface of the housing 14 with adhesive at equal intervals, sothat S-pole and N-pole are positioned. As shown in FIG.2A, acircumferential angle θ of the permanent magnets 40 a,40 b is equal toor less than 150 degrees and more than 120 degrees. Accordingly, gaps208 a,208 b are formed between edge faces of the permanent magnets 40a,40 b that are disposed in the circumferential direction of the housing14. A plate spring 42 is disposed in the gap 208 b. On the other hand, asupport member 72 of a bearing holder 70, which extends toward the pumpsection 12, is disposed in the gap 208 a. The plate spring 42 and thesupport member 72 can prevent permanent magnets 40 a,40 b from shiftingin the circumferential direction. In this embodiment, a distance d(shown in FIG. 2B) between an edge face 41 of the permanent magnets 40a,40 b which face the pump casing 22 and an opening 206 of the dischargeport 204 which faces the permanent magnet 40 a is equal to or less than10 mm.

The armature 50 is rotatably positioned inside two permanent magnets 40a,40 b so that a clearance space is formed as a fuel passage 210 betweeninner surfaces of the permanent magnets 40 a,40 b and an outer surfaceof the armature 50. The armature 50 has a core 52 that is made of thelaminated magnetic steel sheets, and coils wound around the core 52. Thecore 52 has a plurality of magnetic pole cores 54 which are arranged inthe rotation direction of the armature 50. The coils are wound aroundeach of the magnetic pole cores 54. Moreover, the rotary shaft 56 isinserted into a core 52. A metal bearing 24 rotatably supports one endof the rotary shaft 56, and a metal bearing 26 rotatably supports theother end of the rotary shaft 56. The bearing 24 is disposed in the pumpcasing 22, and the bearing 26 is disposed in the bearing holder 70.

The commutator 60 is formed as a plane disk-shape, and is disposed onthe opposite side of the impeller 30 with respect to the armature 50.The commutator 60 has a plurality of segments 62 which are arranged inthe rotation direction of the armature 50. The segments 62 are made ofcarbon, for example, and electrically connected to the coils of thearmature 50. The adjacent segments 62 are separated by a gap or aninsulating resin. This prevents the adjacent segments 62 from connectingelectrically. With this structure, when the armature rotates, eachsegment 62 will make contact with the brush 80 sequentially, and drivecurrent to be supplied to the coils of the armature 50 will becommutated. A terminal 64 is inserted in an end cover 74. Drive currentis supplied to the coils of the armature 50 from an external powersource through the terminal 64, the brush 80, and the commutator 60. Theend cover 74 is caulked at the outer periphery thereof by the edgeportion of the housing 14, as shown in FIG. 1. With this structure, thebearing holder 70 can be held between the end cover 74 and a step 16formed on the inner surface of the housing 14. A discharge port 212 isdisposed on the end cover 74, and accommodates a check valve 90 forpreventing back-flow of fuel discharged from the discharge port 212. Thebearing holder 70 and the end cover 74 are made of resin.

With the above-described structure, fuel discharged from the dischargeport 204 of the pump section 12 will be supplied to the internalcombustion engine through the gap 208 a,208 b, the fuel passage 210 andthe discharge port 212. Thus, fuel pressurized in the pump section 12flows in the motor section 13. Accordingly, the fuel flowing in themotor section 13 cools the motor section 13, and improves the lubricityof a slide member in the motor section 13.

Especially, with the structure of the fuel pump described in the presentinvention, an imaginary line extending straight through the dischargeport in a flow direction of fuel discharging from the discharge portextends into a circumferential gap between two of said permanentmagnets. Accordingly, fuel discharging from the discharge port 204 flowsstraight into the gap 208 b between two permanent magnets 40 a,40 b.

In a first embodiment, as shown in FIG. 2B, an inner inclined surface205 is formed in the discharge port 204 on the front side of therotation direction of the impeller 30. An imaginary line 220 extendingin a flow direction of fuel discharging from the discharge port 204along the inner inclined surface 205 extends between the upstream endsof the adjacent permanent magnets 40 a,40 b. Thus, the imaginary line220 is inclined to the outer surface 23 of the pump casing 22, whichfaces the motor section 13. In this embodiment, an angle α between theimaginary line 220 and the outer surface 23 of the pump casing 22 isequal to or less than 60 degrees and more than 10 degrees. The dischargeport 204 is disposed in the vicinity of the gap 208 b in which the platespring 42 is disposed. The plate spring 42 is made of thin plate so asto reduce the pressure loss of the fuel flowing through the gap 208 b.

In the first embodiment, described above, the imaginary line 220 extendsin a flow direction of fuel discharging from the discharge port 204along the inner inclined surface 205 that is formed in the dischargeport 204 on the front side of the rotation direction of the impeller 30.Moreover, the imaginary line 220 extends between the upstream ends ofthe adjacent permanent magnets 40 a,40 b. With this structure,pressurized fuel that is discharged from the discharge port 204 flowssmoothly into the gap 208 b, which is closer to the discharge port 204.As a result, pressure loss of the fuel flowing into the gaps 208 a,208 bis reduced. At the same time, a noise generated due to fuel flowing fromthe pump section 12 into the motor section 13 is reduced.

In the first embodiment, described above, the angle e of circumferenceof the permanent magnets 40 a,40 b is equal to or less than 150 degreesand more than 120 degrees. Thus, larger gaps 208 a,208 b are formed.Accordingly, the pressure loss of the fuel flowing into the gaps 208a,208 b is reduced.

In the first embodiment, described above, the distance d between theedge face 41 of the permanent magnets which face the pump casing 22 andthe opening 206 of the discharge port 204 which faces the permanentmagnet 40 a is equal to or less than 10 mm. Accordingly, the pumpsection 12 can be closer to the motor section 13. Therefore, the fuelpump 10 can be downsized.

In the first embodiment, described above, the angle α between theimaginary line 220 and the outer surface 23 of the pump casing 22 isequal to or less than 60 degrees and more than 10 degrees. With thisstructure, the direction of fuel flowing in the rotation direction ofthe impeller 30 through the fuel passage 202 a,202 b is not changedsignificantly. Therefore, fuel will be discharged smoothly along theinner inclined surface 205 that is formed in the discharge port 204 onthe front side of the rotation direction of the impeller 30.

Second Embodiment

A fuel pump according to the second embodiment will be described withreference to FIG. 3. The same or similar reference numerals hereafterindicate the same or substantially the same part, portion or componentas the first embodiment.

As shown in FIG. 3, an edge 207 between the inner inclined surface 205of the opening 206 and the outer surface 23 of the pump casing 22 isaxially below the gap 208 b formed between permanent magnets 40 a,40 b.With this structure, fuel discharged from the discharge port 204 flowssmoothly into the gap 208 b. Therefore, pressure loss of the fuelflowing into the gap 208 a,208 b is reduced. At the same time, noisegenerated due to fuel flowing from the pump section 12 into the motorsection 13 is reduced.

The range of the circumferential angle θ of the permanent magnets 40a,40 b, the distance d between the edge face 41 and the opening 206, andthe angle α between the imaginary line 220 and the outer surface 23 inthe second embodiment are the same as described in the first embodiment.

(Variation)

In the above embodiments, the circumferential angle θ of the permanentmagnets 40 a,40 b is equal to or less than 150 degrees and more than 120degrees. However, the angle θ may be defined outside of the above range.

In the above embodiments, the distance d between the edge face 41 andthe opening 206 is equal to or less than 10 mm. However, the distance dmay be defined outside of the above range.

In the above embodiments, the angle α between the imaginary line 220 andthe outer surface 23 is equal to or less than 60 degrees and more than10 degrees. However, the angle α may be defined outside of the aboverange.

In the above embodiments, two permanent magnets are provided. However,four permanent magnets, or the even more than four permanent magnets,may be provided.

Various other modifications and alternations may be made to the aboveembodiments without departing from the spirit of the present invention.Thus, while the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A fuel pump for supplying fuel suctioned from a fuel tank to aninternal combustion engine, comprising: a housing; a plurality ofmagnets that are disposed circumferentially on an inner surface of saidhousing, and forming different magnetic poles alternately; an armaturedisposed rotatably inside the permanent magnets; a rotating memberdisposed on a rotary shaft that is connected with the armature androtates with the rotary shaft by rotating the armature; a pump casingthat accommodates and rotatably supports the rotating member; and adischarge port disposed in the pump casing to discharge fuel pressurizedby the rotation of the rotating member; wherein: an imaginary lineextending straight through the discharge port in a flow direction offuel discharging from the discharge port extends into a circumferentialgap between two of said permanent magnets.
 2. The fuel pump according toclaim 1, wherein: said imaginary line extends along an inner inclinedsurface of the discharge port.
 3. The fuel pump according to claim 1,wherein: an edge between an inner inclined surface of the discharge portand an outer surface of the pump casing is disposed axially below saidcircumferential gap.
 4. A fuel pump for supplying fuel suctioned from afuel tank to an internal combustion engine, comprising: a housing; aplurality of magnets that are disposed circumferentially on an innersurface of said housing, and forming different magnetic polesalternately; an armature disposed rotatably inside the permanentmagnets; a rotating member disposed on a rotary shaft that is connectedwith the armature and rotates with the rotary shaft by rotating thearmature; a pump casing that accommodates and rotatably supports therotating member; and a discharge port disposed in the pump casing todischarge fuel pressurized by the rotation of the rotating member;wherein: an imaginary line extending in a flow direction of fueldischarging from the discharge port along an inner inclined surface ofthe discharge port extends between upstream ends of adjacent permanentmagnets.
 5. The fuel pump according to claim 4, wherein: a distance dbetween an edge face of the permanent magnets which face the pump casingand an opening of the discharge port which faces the permanent magnet isequal to or less than 10 mm.
 6. The fuel pump according to claim 4,wherein: there are two permanent magnets.
 7. The fuel pump according toclaim 6, wherein: a circumferential angle θ of the permanent magnets isequal to or less than 150 degrees and more than 120 degrees.
 8. The fuelpump according to claim 4, wherein: an angle between the imaginary lineand the outer surface of the pump casing is equal to or less than 60degrees and more than 10 degrees.
 9. A fuel pump for supplying fuelsuctioned from a fuel tank to an internal combustion engine comprising:a housing; a plurality of magnets that are disposed circumferentially onan inner surface of said housing, and forming different magnetic polesalternately; an armature disposed rotatably inside the permanentmagnets; a rotating member disposed on a rotary shaft that is connectedwith the armature and rotates with the rotary shaft by rotating thearmature; a pump casing that accommodates and rotatably supports therotating member; and a discharge port disposed on the pump casing todischarge fuel pressurized by the rotation of the rotating member;wherein: an edge between an inner inclined surface of the discharge portand an outer surface of the pump casing being disposed axially below acircumferential gap formed between two of said permanent magnets. 10.The fuel pump according to claim 9, wherein: a distance d between anedge face of the permanent magnets which face the pump casing and anopening of the discharge port which faces the permanent magnet is equalto or less than 10 mm.
 11. The fuel pump according to claim 9, wherein:there are two permanent magnets.
 12. The fuel pump according to claim11, wherein: a circumferential angle θ of the permanent magnets is equalto or less than 150 degrees and more than 120 degrees.